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Analysis of a water drop on a hydrophobic surface

Analysis of a water drop on a hydrophobic surface

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Analysis of a water drop on a hydrophobic surface

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  1. Analysis of a water drop on a hydrophobic surface Jordan Allen-Flowers Mitch Wilson Graduate Program in Applied Mathematics University of Arizona December 9,2009 Advisors: Dr. Alain Goriely, Robert Reinking

  2. Outline • Introduction • Methods • Theory • Results • Horizontal deformation • Contact time • Discussions • Conclusions/Future Work

  3. Introduction • Water-drop phenomena • Hydrophobic surface • Three behaviors: • Bouncing • Crowning • Splashing

  4. Research Goals • Discover relationships between different parameters • Horizontal deformation • Contact time • Compare to published results

  5. Applications • Inkjet printing • Fluid transport • Blood spatter at a crime scene • Water removal on leaves

  6. Methods • Water-drop system • Pipettes and syringes • Test slides • Pressure bulbs • Camera and software • High-speed camera • Photron Motion Tools, ImageJ software • 1000W lamp

  7. Theory: Maximum deformation • Weber number: • U is impact velocity • D is drop diameter • ρ, σ are density and surface tension • Ratio of kinetic energy to surface energy • Ranges from ~1 to ~50

  8. Three different scaling laws for maximal deformation: • All kinetic energy is transformed to surface energy • Kinetic energy is dissipated by viscosity • Gravity puddle approach

  9. Theory: Contact time • Balancing inertia and capillarity yields: • This can also be rewritten as: • But implies that τ is independent of U

  10. Results- Horizontal Deformation

  11. More results for max deformation

  12. Results- Contact Time

  13. More results for contact time

  14. Conclusions • The water-drop phenomena- quick, but intricate • Our data was consistent with the theory of some authors • Future work • Surface analysis • Different liquids • Pinch-off phenomenon • We would like to thank Dr. Alain Goriely andRob Reinking, who made this research possible.

  15. References • Rein, M. 1993. "Phenomena of liquid drop impact on solid and liquid surfaces" Fluid Dyn. Res. 12, 61-93. • Okumura, K., Chevy F., Richard, D., Quere, D., Clanet, C. 2003. "Water spring: A model for bouncing drops" Europhys. Let. 62, 237-243. • Clanet, C., Beguin, C., Richard, D., Quere, D. 2004. "Maximal deformation of an impacting drop" J. Fluid Mech. 517, 199-208. • Richard, D., Clanet, C., Quere, D. 2002. "Contact time of a bouncing drop" Nature 417, 811. • Chandra, S., Avedisian, C.T. 1991. "On the collision of a droplet with a solid surface" Proc. Royal Soc. London A 432, 13.